<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="utf-8">
	<meta http-equiv="x-ua-compatible" content="ie=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="examples-styles.css"/>

	<link rel="icon" href="favicon.ico" type="image/x-icon"/>
	<title>abcjs: Modify Synth Input Demo</title>

	<style>
		main {
			max-width: 770px;
			margin: 0 auto;
		}
		.abcjs-cursor {
			stroke: red;
		}
	</style>

	<script src="../dist/abcjs-basic.js" type="text/javascript"></script>
	<script type="text/javascript">
		var abc = "T: Cooley's\n" +
			"%%barnumbers 1\n" +
			"M: 4/4\n" +
			"L: 1/8\n" +
			"Q: 1/4=120\n" +
			"R: reel\n" +
			"K: Emin\n" +
			"EBBA B2 EB|~B2 AB dBAG|FDAD BDAD|FDAD dAFD|\n" +
			"EBBA B2 EB|B2 AB defg|afe^c dBAF|DEFD E2 gf|\n" +
			"|eB B2 efge|eB B2 gedB|A2 FA DAFA|A2 FA defg|\n" +
			"eB B2 eBgB|eB B2 defg|afe^c dBAF|DEFD E2 D2||";

		var synth = new ABCJS.synth.CreateSynth();

		function load() {
			// First draw the music - this supplies an object that has a lot of information about how to create the synth.
			// NOTE: If you want just the sound without showing the music, use "*" instead of "paper" in the renderAbc call.
			var visualObj = ABCJS.renderAbc("paper", abc, {
				responsive: "resize" })[0];

			var startAudioButton = document.querySelector(".activate-audio");
			var stopAudioButton = document.querySelector(".stop-audio");
			var explanationDiv = document.querySelector(".suspend-explanation");

			startAudioButton.addEventListener("click", function() {
				startAudioButton.setAttribute("style", "display:none;");
				explanationDiv.setAttribute("style", "opacity: 0;");
				if (ABCJS.synth.supportsAudio()) {
					stopAudioButton.setAttribute("style", "");

					// An audio context is needed - this can be passed in for two reasons:
					// 1) So that you can share this audio context with other elements on your page.
					// 2) So that you can create it during a user interaction so that the browser doesn't block the sound.
					// Setting this is optional - if you don't set an audioContext, then abcjs will create one.
					window.AudioContext = window.AudioContext ||
						window.webkitAudioContext ||
						navigator.mozAudioContext ||
						navigator.msAudioContext;
					var audioContext = new window.AudioContext();
					audioContext.resume().then(function () {
						// In theory the AC shouldn't start suspended because it is being initialized in a click handler, but iOS seems to anyway.

						synth.init({
							audioContext: audioContext,
							visualObj: visualObj,
							options: {
								sequenceCallback: sequenceCallback
							}
						}).then(function () {
							synth.prime().then(function () {
								synth.start();
							});
						}).catch(function (error) {
							console.log("Audio Failed", error);
						});
					});
				} else {
					var audioError = document.querySelector(".audio-error");
					audioError.setAttribute("style", "");
				}
			});

			stopAudioButton.addEventListener("click", function() {
				startAudioButton.setAttribute("style", "");
				explanationDiv.setAttribute("style", "");
				stopAudioButton.setAttribute("style", "display:none;");
				synth.stop();
			});

			function sequenceCallback(tracks) {
				// The beats are 0.25 long so the amount of swing needs to be between 0 and 0.125,
				// but practically it needs to be a bit smaller so that it doesn't sound like a grace note.
				var swing = 0.1 - 0.1 / document.getElementById("swing").value;
				document.getElementById("coefficient").innerText = swing;
				var track = tracks[0];
				for (var i = 0; i < track.length; i++) {
					var event = track[i];
					if (event.start % 0.25) {
						// This is the off beat
						event.start += swing;
					} else {
						// This is the beat
						event.end += swing;
					}
				}
			}
		}
	</script>
</head>
<body onload="load()">
  <header>
    <img src="https://paulrosen.github.io/abcjs/img/abcjs_comp_extended_08.svg" alt="abcjs logo">
    <h1>Modify Synth Input</h1>
  </header>
  <div class="container">
    <main> 
      <p>Demonstration of changing the synth on the fly if you want to make adjustments.</p>
      <p>This example adds some "swing" to the tune.</p>
        <p><label>Amount of swing (1 to 6): <input id="swing" type="number" min="1" max="6" value="2"></label></p>
        <p><label>Calculated swing coefficient:</label> <code id="coefficient">??</code></p>
      <div id="paper"></div>
      <p class="suspend-explanation">Browsers won't allow audio to work unless the audio is started in response to a user action. This prevents auto-playing web sites. Therefore, the
        following button is needed to do the initialization:</p>
      <button class="activate-audio">Activate Audio Context And Play</button>
      <button class="stop-audio" style="display:none;">Stop Audio</button>
      <div class='audio-error' style="display:none;">Audio is not supported in this browser.</div>
    </main>
  </div>
</body>
</html>
